Prosocial performances are viewed as operant behaviors influenced by their social consequences. To investigate the sources of low baserates of young children's sharing, structured play situations in nursery schools will be used to examine social antecedents and consequences for sharing refusals to share. The Hartshorne and May service tests will be administered to 5-12-year-old children to determine (a) helping rates and patterning of helping as a function of age and gender; (b) sexual stereotyping in perceived helpfulness; (c) the correspondence between moral judgments and helpfulness; and (d) the generality and durability of modeling effects. Incorrect motivational attributions may be responsible for the common belief in the existence of a class of altruistic behaviors that occur independent of reinforcement contingencies. The effects of reward and punishment on motivational attributions regarding helping will be investigated, both with the child as observer of charitable responding by others and with the child as the donor, reporting on his own motivation. The relationship between causal attributions and the durability and generality of charitable behavior will also be studied.